What Happens When Cladding Can’t Breathe?
- Alder Homes Ltd
- Mar 25
- 5 min read
When cladding cannot drain and ventilate properly, moisture can become trapped inside wall cavities. Over time, this can lead to timber decay, mould growth, corrosion, reduced insulation performance, and expensive remediation work. The damage is often hidden and may not become visible until significant deterioration has occurred.
A Home Should Protect You from the Weather — But It Also Needs to Manage It
As wind-driven rain, humidity, and temperature swings are part of everyday life, your cladding system isn’t just there to keep water out. It’s there to control how moisture behaves over time.
One of the biggest issues we see is what happens when that system stops working.
Key Insights
Trapped moisture is one of the leading causes of hidden structural damage.
Damage often happens slowly and is usually invisible until it’s serious.
Cladding systems are designed to drain and dry, not just seal.
Moisture entering a wall is normal; how it’s managed is what matters.
Small interruptions to airflow or drainage can trap moisture long-term.
The Problem: Moisture Has Nowhere to Go!
No matter how well a home is built, moisture will always find its way in. Whether it’s wind-driven rain getting past the cladding, condensation forming inside the wall from temperature changes, or small amounts of water tracking through gaps, moisture is persistent.
A well-designed system anticipates this and manages it. It allows moisture that gets in to safely drain out and dry. The problem begins when that pathway is interrupted—when moisture enters but can’t escape.
Not All Moisture Comes from Outside
Everyday living creates warm, moisture-laden air in your home. Showers, cooking, and even breathing contribute to this humidity. This air naturally moves into wall cavities. When it meets colder surfaces within the wall, it cools and releases that moisture as condensation. Without the ability to dry out, this moisture can build up over time, even in the absence of any visible leaks.
What Happens When Moisture Gets Trapped
Once moisture is inside and can’t escape, the environment inside the wall changes. It becomes consistently damp.
That’s when materials start behaving differently:
Moisture levels rising in timber framing make it susceptible to decay.
Mould and mildew begin forming in dark, enclosed spaces.
Fixings and connectors exposed to prolonged moisture accelerate corrosion.
Insulation loses effectiveness as it becomes damp.
Drying cycles stop, meaning materials never return to a stable condition.
And importantly—none of this is visible from the outside.
The Real Cost of Getting It Wrong
We’ve already seen the impact of this through past weathertightness issues. We’re still seeing it today in newer homes where systems haven’t been installed or maintained properly.
What could have been a small detailing issue early on can quickly turn into a full remediation project. When moisture is trapped long-term, repairs often go far beyond a simple fix. This can involve removing cladding, replacing damaged framing, rebuilding sections of the structure, and reinstalling compliant systems to ensure the home performs properly.
Where Good Intentions Go Wrong
Most moisture problems don’t come from major failures. They come from small, well-intentioned decisions that cause homeowners to accidentally trap water in. Here are some of the most common errors we see:
Blocking brick weep holes: Small gaps in brick mortar are there on purpose, allowing water to drain out and air to circulate. Filling or sealing them traps moisture inside the wall.
Piling soil, mulch, or paving up against cladding: Cladding needs clearance at the bottom to allow water to drain. When ground levels are too high, moisture has nowhere to escape and can be drawn back into the wall.
Sealing everything with silicone “just to be safe”: Not all gaps are meant to be sealed. Some are designed as drainage or ventilation paths. Sealing them can block the system from working properly.
Sealing up the bottom of cladding or joinery: Water is designed to exit at the bottom. If this gets sealed, moisture gets trapped inside instead of draining out.
Painting or coating over drainage gaps: Paint, plaster, or coatings can unintentionally block small but critical exit points for moisture.
Installing insulation or retrofits that block cavities: Even something like insulation pushed too tightly into a cavity can stop airflow and drainage.
Adding decks, paths, or landscaping without considering drainage: These can cover or block the bottom edge of cladding where water is meant to escape.
How to Protect Your Home
Homes that perform well long-term are rarely the result of chance. They come from experience—understanding how moisture moves, how materials behave, and how small details influence the bigger picture.
It’s not about using expensive products; it’s about better building, proven methods, and proper execution.
That's one of the reasons working with a Licensed Building Practitioner (LBP) is so important. An experienced LBP understands the building science behind modern cladding systems, drainage cavities, ventilation gaps, flashings, and weatherproofing details that help protect your home from moisture-related issues.
By getting the details right from the start, your investment is protected for years to come.
What Helps Prevent Moisture Problems Behind Cladding?
Designing with moisture in mind from the outset
Ensuring the cladding system, cavity, and detailing all work together before construction even begins.
Installing true cavity systems correctly
Not just having a cavity, but making sure it’s continuous, unobstructed, and able to drain and ventilate properly.
Precision flashing and junction detailing
Around windows, doors, penetrations, and transitions—directing water out, not giving it a path in.
Correct material selection and placement
Using the right products in the right locations so they can perform as intended over time.
Colour selection matters too
Colour choice can also affect cladding performance. That’s why many manufacturers have Light Reflectance Value (LRV) requirements that should be checked before choosing an exterior colour.
Integration between new and existing work
Making sure renovations and additions don’t interrupt how the original structure manages moisture.
Attention to the small details that are often missed
It’s rarely one big issue; it’s the accumulation of small oversights that lead to failure!
Done properly, a home doesn’t just look good when it’s finished—it continues to perform, dry, and protect itself for years to come.
Cladding Isn’t Just a Barrier; It’s Part of a System Designed to Manage Water, Not Just Stop It
It’s not the presence of moisture that causes the damage; it’s when it has nowhere to go.
If you’ve read this and started noticing things around your own home, that’s usually the right time to get it looked at. We’re always happy to take a look and point you in the right direction.
Why Moisture Management Matters More Than Most Homeowners Realise
In Auckland, where the weather can be unpredictable, it’s crucial to ensure your home is equipped to handle moisture effectively. By understanding the importance of moisture management, you can protect your investment and maintain a healthy living environment.
If you need assistance with your home’s cladding system or any renovations, feel free to reach out. We’re here to help you create a home that stands the test of time.
Frequently Asked Questions About Cladding and Moisture
Is it normal for water to get behind cladding?
Yes. Modern cladding systems are designed with the expectation that some moisture may pass behind the outer surface. The important factor is ensuring it can drain and dry safely.
What is a cavity behind cladding?
A cavity is a small drainage and ventilation gap between the cladding and the building wrap. It helps moisture escape and allows airflow behind the cladding.
Can trapped moisture damage timber framing?
Yes. Prolonged moisture exposure can lead to timber decay, mould growth, corrosion of fixings, and reduced building performance.
How do I know if my cladding has moisture problems?
Common warning signs include staining, swelling, cracking, mould, musty smells, deteriorating paint, or elevated moisture readings. However, many moisture issues remain hidden until investigated.
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